Invariably, I awaken shortly before the alarm clock goes off. It never fails, and it also means my spouse is not awakened by the ringing alarm because I shut it off first. A couple of times, our alarm clock was mis- or never set, yet I awakened at the proper time--even though it may have been earlier or later than the time I had decided on during the prior evening. I've concluded that Grace knows the time I need to arise better than I do. The last time, I didn't set the alarm clock and sure enough, I was awakened at the right time. [Grace is also a very good co-driver--sometimes warning others I am going to do something stupid so they can get out of the way!]
An internet search of "guardian angel" and alarm clock produced interesting tidbits of information on St. Padre Pio's guardian angel, including:
Father Alessio Parente was assigned to assist the fragile monk from the chapel to his monastic cell every day. But Father Parente had a habit of oversleeping. Often he wouldn't hear his alarm clock or, half awake, he would switch it off. "Every time I overslept," he says, "I heard a voice in my sleep saying, 'Alessio, Alessio, come down!' and a knocking at my door....St. Padre Pio told Fr. Allesio that he sent his guardian angel to awaken Fr. Allesio.
Here is an important twice-daily prayer I say to my guardian angel:
Angel of God, my guardian dear,
To whom God's love commits me here.
Ever this day [night], be at my side,
To light and guard, to rule and guide. Amen.